Hey I've got two questions (no answers so ones more of just double checking some working!)

Firstly can someone have a look over this for me:

my reasoning is this

if we change the parameter now by letting

we then have

so this would be a circle of radius centered on c

as
(does this get around the problem that can be negative?)

or did I screw up somewhere!

and for the second question any chance of a little hint because I cant see where to start with this

for this ive worked out that the final condition implys that if each of the numbers a,b,c were written as etc.
then but I cant see a way to apply it so any chance of a hint

many thanks

Simon

Your solution to the first one is fine. however there is a neater approach to the 1+ti business. say then then it is easier to simplify . Also I don't see how P being negative would be a problem.

part two should be treated as a vector problem.

firstly is real therefore it may make sense to write where is a real constant. so . treating a and b as vectors it should be clear that this is the equation of a line. however pay attention to the range of .